Donald Trump and his children are using his presidential influence to promote the various business dealings across the family. Even the daughter, Ivanka was promoting her jewelry during the campaign. There needs to be a clear defined separate of the president from any business connections or influence. Even the appearance of promotion could impact business dealings.
It is undeniable that Trump will use his presidency to increase his own finances and boost his businesses. It's good business sense to do it, even though it seems shady to use the presidency to further his own personal gains. Being made president will only increase his greed, thus he will use his position to create wealth for himself in any way he can.
It was always going to be the case that Mr. Trump would use his position of power to benefit his businesses. Any American with a functioning brain would have known that. Even if he moves the business ownership to other parts of his family it doesn't make a difference. Trump is a man who claims to not have paid any tax for 20 years, there is only one way he was going to behave should he get in to power.
Trump's new position as President will take a great deal of time away from his business ventures. He is already one of the most successful businessmen ever. He didn't need the Presidency in order to find ways to meet with important people and finalize business deals. He will be distracted in office.